This thesis examines the toxicological characteristics of suicide in Hungary and Japan, focusing on the substances involved and how patterns differ between the two countries. It shows that in Hungary, medication overdose—especially involving benzodiazepines, antidepressants, and antipsychotics—is the primary toxicological cause of suicide, often exacerbated by alcohol use. In contrast, Japan demonstrates a prominent role of gaseous methods such as carbon monoxide and hydrogen sulfide, although medication overdoses remain significant. The study highlights how cultural, social, and healthcare system differences—such as prescribing practices and access to means—influence suicide methods. It also identifies major challenges in forensic toxicology, including limited autopsy rates and difficulties in interpreting postmortem findings. Finally, the thesis proposes prevention strategies, emphasising safer prescribing, alcohol control, improved toxicological investigation, and coordinated public health interventions to reduce suicide mortality.